1. Technical Field
Illustrative embodiments described herein generally relate to an image forming apparatus such as a digital multifunction printer, a digital copier, a facsimile machine, or a printer, a print processing method employed in the image forming apparatus, and a computer-readable recording medium storing a program for causing a CPU that controls the image forming apparatus to implement functions relating to the illustrative embodiments.
2. Description of the Related Art
Many image forming apparatuses are equipped with the capability to enhance the security of printed documents. One such capability is called marking. Marking typically includes four main functions: a manipulation detection function, an unauthorized copy guard function, a security tracing function, and a refresh copy function.
The manipulation detection function detects whether or not contents of an input document have been manipulated. Specifically, the manipulation detection function embeds marking data in image data of the input document, reads the image data of the input document in which the marking data is embedded, and compares the image data to the marking data embedded in the image data to detect whether or not the input document has been manipulated.
The unauthorized copy guard function embeds marking data in image data of a confidential document to prevent disclosure of the document to the general public through copying or mail/facsimile transmission when printing the document. Further, the unauthorized copy guard function reads the image data in which the marking data is embedded to control operations performed on the document, such as copying, mail/facsimile transmission, or storing, based on the marking data.
The security tracing function embeds a marking image indicating trace data in a document to be printed. The trace data indicates how the document is used, by whom, when, and where. Further, the security tracing function reads image data of the document in which the marking image indicating the trace data is embedded to display the trace data and store the trace data as a log.
The refresh copy function embeds marking data indicating that an original document is stored in a storage medium (such as a hard disk drive (HDD)) in a document to be output when printing the document, so that the original document from which, for example, a handwritten memo is removed, can be easily obtained. Further, the refresh copy function reads image data of the output document in which the marking data is embedded to print out the original document stored in the storage medium indicated in the marking data. Accordingly, the original document without the handwritten memo is obtained even when the handwritten memo is included in an input document.
Because the above-described marking function is for enhancing security for printing operations, it is also important to enhance security for a log (history) when a print job fails or is canceled.
For example, published unexamined Japanese Patent Application Nos. (hereinafter referred to as JP-A-) 2007-158947, 2006-014280, and 2007-306229 respectively disclose the manipulation detection function as the marking function. Specifically, the above-described patent documents disclose how to generate marking data using certain codes, embed the marking data in a document, and detect the marking data thus embedded.
However, although how to perform the marking function using certain codes and algorithms is disclosed, requirements for performing the marking function are not disclosed in the above-described patent documents.
More specifically, because the marking function is performed on image data, requirements for properly performing the marking function are needed in order to perform the printing operation using the marking function with smaller memory size when implementation of the marking function is specified simultaneously with other operations. Such operations include, for example, implementation of an image processing function that performs normal image processing such as compression of image data using compression codes, or banding that divides the image data into bands.
Because it is used for enhancing security for the printing operation, the marking function is required to be more reliably performed than the normal printing operation.
Specifically, exclusive control is required to be performed to prohibit unreliable performance of the marking function in order to protect benefits of the user. When exclusive control is performed, it is necessary to report performance of exclusive control to the user and carefully record such performance in a log.
Another approach is a technique relating to inconsistency of parameters, that is, exclusive control, during printing operations. JP-A-2007-329734 discloses how to perform exclusive control when multiple parameters of print jobs are individually specified, how to use functions of providing punched holes or staples included in an image forming apparatus relative to image data input from an external device without using a printer driver, and operations performed when functions set through a control panel of the image forming apparatus do not coincide with the parameters of the print jobs input from the external device.
However, although disclosing how to perform the functions included in the image forming apparatus relative to the image data input from the external device, JP-A-2007-329734 does not disclose exclusive control for enhancing security for the printing operations such as the marking function.